Cases include efforts to push governments for more aggressive national policies to reduce or prevent greenhouse gas emissions

LONDON, May 23 (Thomson Reuters Foundation) - A growing number of people are going to the courts to try to overturn government decisions seen to exacerbate climate change, according to a global survey of climate change litigation published on Tuesday.

The cases range from efforts to push governments for more aggressive national policies to reduce or prevent greenhouse gas emissions to lawsuits over the expansion of airports and coal mines, or concerning the development of renewable energy generation facilities.

Some 884 climate change cases had been filed by March in 24 countries in Africa, Asia, Pacific, Europe and the Americas. The United States had the highest number of cases - 654 - according to the survey carried out by U.N. Environment and the Columbia Law School's Sabin Center for Climate Change Law.

A survey of climate change-related lawsuits decided before 2014 found cases in just 12 countries, the researchers said.

"Judicial decisions around the world show that many courts have the authority, and the willingness, to hold governments to account for climate change," said Michael Burger, executive director of the Sabin Center.

"In the United States, climate change litigation has been absolutely essential," he said, citing an early lawsuit demanding the U.S. Environmental Protection Agency regulate greenhouse gas emissions, and a recent case claiming a constitutional right to a stable climate system.

"Similar litigation all over the world will continue to push governments and corporations to address the most pressing environmental challenge of our times," Burger said in a statement.

About 177 countries recognise the right of citizens to a clean and healthy environment, and courts are increasingly being asked to define the implications of this right in the age of climate change, the researchers said.

With the Paris Agreement to tackle climate change set to come into effect in 2018, citizens, companies and non-governmental organisations can now argue in some jurisdictions for concrete measures to mitigate climate change.

Governments are nearly always the defendants in climate change cases, and many lawsuits are filed by individuals and NGOs, the survey found.

In the future, cases related to the rights of people forced to leave their homes because of climate change are expected to increase, with some predicting the number of "climate refugees" could reach as high as 1 billion people by 2050, the researchers said.

"It's patently clear we need more concrete action on climate change, including addressing the root causes and helping communities adapt to the consequences," said Erik Solheim, head of U.N. Environment.

"The science can stand up in a court of law, and governments need to make sure their responses to the problem do too," he added. (Reporting by Alex Whiting @Alexwhi, Editing by Laurie Goering.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, climate change, resilience, women's rights, trafficking and property rights. Visit http://news.trust.org/climate)